Mechanism of photocatalytic oxidation of gaseous ethanol

2007 ◽  
Vol 61 (1) ◽  
Author(s):  
C. Shao ◽  
D. Pan ◽  
R. Zhang ◽  
H. Hou
Keyword(s):  
Water Vapour ◽  
Photocatalytic Oxidation ◽  
Oxidation Mechanism ◽  
Ethyl Formate ◽  
Direct Oxidation ◽  
Partial Pressures ◽  
Film Reactor ◽  
Carrier Gases ◽  
Positive Hole ◽  
Dioxide Film

AbstractA photocatalytic film reactor with a titanium dioxide film was used for oxidation of gaseous ethanol at 253.7 nm. The influences of partial pressures of oxygen and water vapour in different carrier gases were studied. The rate of photocatalytic oxidation of ethanol was significantly affected by the content of oxygen but water vapour had no effect. It was suggested that the photocatalytic transformation of ethanol follows a direct oxidation mechanism where the interaction of ethanol with positive hole gives first cationic free radical of ethanol, which is converted by multipathway reactions with oxygen to acetaldehyde, ethyl formate, and ethyl acetate.

scholarly journals A facile and effective method for preparation of 2.5-furandicarboxylic acid via hydrogen peroxide direct oxidation of 5-hydroxymethylfurfural

2017 ◽  
Vol 19 (1) ◽  
pp. 11-16 ◽  
Author(s):  
Shuang Zhang ◽  
Long Zhang
Keyword(s):  
Hydrogen Peroxide ◽  
Reaction Time ◽  
Oxidation Mechanism ◽  
Molar Ratio ◽  
Alkaline Condition ◽  
Optimal Parameters ◽  
Direct Oxidation ◽  
Reaction Parameters ◽  
Alkaline Conditions ◽  
Furandicarboxylic Acid

Abstract In this paper, 2,5-furandicarboxylic acid (FDCA) was efficiently prepared by the direct oxidation of 5-hydroxymethylfurfural (5-HMF) using hydrogen peroxide (H2O2) in alkaline conditions without any catalysts. The effects of reaction parameters on the process were systematically investigated and the optimal parameters were obtained as follows: molar ratio of 5-HMF:KOH:H2O2 was 1:4:8, reaction temperature and reaction time were determined as 70°C and 15 minutes, respectively. Under these conditions, the yield of FDCA was 55.6% and the purity of FDCA could reach 99%. Moreover, we have speculated the detailed oxidation mechanism of 5-HMF assisted by hydrogen peroxide in alkaline condition to synthesize FDCA.

Synthesis and study of diaboleïte

1968 ◽  
Vol 36 (283) ◽  
pp. 933-939 ◽  
Author(s):  
R. E. Winchell ◽  
H. E. Wenden
Keyword(s):  
Water Vapour ◽  
Atmospheric Pressure ◽  
Stable Phase ◽  
Line Position ◽  
Natural Mineral ◽  
X Ray ◽  
Partial Pressures ◽  
Cell Dimensions ◽  
Natural And Synthetic

SummaryDiaboleïte has been synthesized between 25 and 100° C at atmospheric pressure and approximate water vapour partial pressures of 14·7 lb/in2. Under similar conditions at 170° C cumengéite appears to be the stable phase produced from a diaboleïte composition. Synthetic diaboleïte is much simpler morphologically than the natural mineral but the hemimorphic symmetry is more clearly demonstrated morphologically in the artificial specimens. A comparison of X-ray powder data for natural and synthetic diaboleïte shows almost exact detailed correspondence in line position and intensity between 0 and 180° 2θ. The cell dimensions obtained from X-ray powder data are a 5·869 ± 0·002 Å and c 5·495 ± 0·003 Å.

Photocatalytic Oxidation Mechanism of As(III) on TiO2: Unique Role of As(III) as a Charge Recombinant Species

2010 ◽  
Vol 44 (23) ◽  
pp. 9099-9104 ◽  
Author(s):  
Wonyong Choi ◽  
Jiman Yeo ◽  
Jungho Ryu ◽  
Takashi Tachikawa ◽  
Tetsuro Majima
Keyword(s):  
Photocatalytic Oxidation ◽  
Oxidation Mechanism ◽  
Unique Role ◽  
A Charge

scholarly journals Aqueous Photocatalytic Oxidation of Lignin: The Influence of Mineral Admixtures

2007 ◽  
Vol 2007 ◽  
pp. 1-7 ◽  
Author(s):  
Elina Portjanskaja ◽  
Sergei Preis
Keyword(s):  
Titanium Dioxide ◽  
Photocatalytic Oxidation ◽  
Catalyst Support ◽  
Oxidation Mechanism ◽  
Ion Concentration ◽  
Mineral Admixtures ◽  
Oh Radicals ◽  
Ferrous Ions ◽  
The Difference ◽  
The One

The photocatalytic oxidation (PCO) of UV-irradiated aqueous solutions containing lignin onTiO2was studied for the influence of ferrous ions. The addition ofFe2+, up to 2.8 mgL−1, to the acidic lignin solution leads to the drastic, for about 25%, increase in PCO efficiency. A further increase in ferrous ion concentration results in a decrease in PCO efficiency of lignin. The maximum PCO efficiency, up to 9.2 mgW−1h−1, was observed in neutral and slightly basic media: the oxidation mechanism with OH-radicals seems to prevail. Also, the difference in the PCO performance with a different attachment mode of titanium dioxide on the catalyst support was observed. Sprayed catalyst exhibited 1.5 times higher efficiency than the one attached by submersion, although sprayed one was easily resuspended in acidic lignin solutions. The efficiency of the N-doped photocatalyst active in visible light was observed to be negligible with lignin.

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